Mechanisms that clear mutations drive field cancerization in mammary tissue

Sep 21, 2026

Uploaded by Theodore

Oncogenic mutations are common in healthy tissue but seldom form tumors, and the protective mechanisms that prevent mutant expansion remain unclear. Using lineage tracing in mouse mammary tissue, the study maps wild-type and Brca1−/−;Trp53−/− cells as they lose and spread within ducts. Clonal structure shows small self-renewing units that continually shed descendants, while oestrous-cycle remodeling cooperatively and stochastically removes many mutant clones. Surviving minorities expand until duct geometry restrains growth, collectively limiting transformation through field cancerization.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages36

Reading Time1 h 31 min

AccessFree to download

Introduction

Mutant cell abundance and the problem of protection

Methods and experimental approach

Lineage tracing and clonal analysis

Findings

Duct organization and stem cell-descendant units

Oestrous-cycle remodeling and mutant clone elimination

Geometry-restrained expansion and field cancerization

Implications

Article Mechanisms that clear mutations drive field cancerizationin mammary tissue | [https://doi.org/10.1038/s41586-024-07882-3](https://doi.org/10.1038/s41586-024-07882-3)
Received: 13 December 2022 Accepted: 26 July 2024 Published online: 4 September 2024 Open access
Check for updates | Marta Ciwinska1,21, Hendrik A. Messal2,21, Hristina R. Hristova2,21, Catrin Lutz2, Laura Bornes2, Theofilos Chalkiadakis3, Rolf Harkes4, Nathalia S. M. Langedijk2, Stefan J. Hutten2,
RenéeX. Menezes5, Jos Jonkers2, Stefan Prekovic3, Grand Challenge PRECISION consortium*, Benjamin D. Simons6,7,8,22✉, Colinda L. G. J. Scheele1,22✉ & Jacco van Rheenen2,22✉
Oncogenic mutations are abundant in the tissues of healthy individuals, but rarely form tumours1–3. Yet, the underlying protection mechanisms are largely unknown. To resolve these mechanisms in mouse mammary tissue, we use lineage tracing to map the fate of wild-type and Brca1−/−;Trp53−/− cells, and find that both follow a similar pattern of loss and spread within ducts. Clonal analysis reveals that ducts consist of small repetitive units of self-renewing cells that give rise to short-lived descendants. This offers a first layer of protection as any descendants, including oncogenic mutant cells, are constantly lost, thereby limiting the spread of mutations toa single stem cell-descendant unit. Local tissue remodelling during consecutive oestrous cycles leads to the cooperative and stochastic loss and replacement of self-renewing cells. This process provides a second layer of protection, leading to the elimination of most mutant clones while enabling the minority that by chance survive to expand beyond the stem cell-descendant unit. This leads to fields of mutant cells spanning large parts of the epithelial network, predisposing it for transformation. Eventually, clone expansion becomes restrained by the geometry of the ducts, providing a third layer of protection. Together, these mechanisms act to eliminate most cells that acquire somatic mutations atthe expense of driving the accelerated expansion of a minority of cells, which can colonize large areas, leading to field cancerization. | | | --- | --- | --- | | The acquisition of genetic aberrationsin oncogenesand tumoursup- | | oestrous cycle, the mouse variant of the menstrual cycle, hormones | | pressor genes is considered fundamental to tumorigenesis. Seventy | | acton HR+ luminal cells, triggering the secretion of mitogenic paracrine | | per cent of women with germline mutations in BRCA1 orBRCA2, two | | signalling factors9–11. These factors initiate coordinated rounds of prolif- | | well-studied tumour suppressor genes, develop breast cancer by the | | eration, also in basal and luminal cells negative for HR, thereby driving | | age of 80 (refs.4,5). However, sequencing studies show that mutant | | the growth of side branches, referred to as alveolar buds. In pregnancy, | | cells with alterationsin key driver genes, such asP53, are abundant in | | these side branches progress into lobuloalveolar structures, capable of | | a wide variety of tissues in healthy individuals, includingthe breast1–3,6. | | milk production and secretion12,13. However, outside pregnancy, these | | This high abundance of mutant cells could be associated with a high | | side branches regress through coordinated cell death atthe end of the | | frequency of independent mutagenic events, or could arise from a | | cycle14,15. Thus, throughout life, each oestrous cycle drives coordinated | | minority of mutant cells that spread over large fieldsoftissue. With the | | rounds of localized proliferation and cell death9,16–21. | | latter, such behaviour has the potential to create areas predisposed to | | Long-term maintenance under conditions of continuous remodel- | | transformation, a process referred to as field cancerization, and may | | ling requires self-renewal activity, and is therefore thought tobe driven | | playa crucial role in t

FAQs

Why are oncogenic mutations unlikely to become tumors in healthy tissue?

Oncogenic mutations are abundant, yet tumors rarely form because protective mechanisms limit mutant spread and persistence. The mechanisms were largely unknown prior to this work.

What experimental strategy was used to track mutant and wild-type cells?

The study uses lineage tracing in mouse mammary tissue and clonal analysis to map the fate of wild-type versus Brca1−/−;Trp53−/− cells as they behave within ducts.

How do the duct’s organization and oestrous-cycle remodeling affect mutant expansion?

Ducts are built from small self-renewing units whose descendants are short-lived, so mutants are constantly cleared. Consecutive oestrous cycles then drive cooperative, stochastic loss and replacement of self-renewing cells, eliminating most mutant clones while allowing a minority that survives to expand. Geometry of the ducts eventually restrains expansion, shaping field cancerization.

Sep 21, 2026

Uploaded by Theodore